I looked but I could not find this one. I would like to see an option added to the UI to close all vaults. I typically have 1-3 vaults open at the time. When I get ready to log off I have close each vault individually. Would it be possible to add a feature to close all with one click?
Please have a look at the taskbar context menü of cryptomator (right click on taskbar icon).
Here you find the function to close/lock all vaults. (At least on Windows, I cannot check other OS)
Yet another possibility: Just quit the application, it should then ask you to lock all remaining vaults first.